Mice can get through the smallest openings. In an old house... especially with a stone foundation... I don't think you can ever be mouse-free.
I have three "working" cats and while they get most of the varmints they don't get 'em all.
We have two small cupboards above our stove. I kept a box of raisin bran up there, and, being way up high, forgot about it. At one point we noticed a really bad odor coming from somewhere in the kitchen. Not the fridge. Well, it subsided after a while. Didn't think anything more about it. Several months later, I remembered the raisin bran and took the box down, to find it was empty except for a mouse carcass. That was the smell!
Oh, and there's nothing quite like the feeling you get while walking to the bathroom in the middle of the night, and stepping on something small and soft and squishy. Yup. An offering of dead mouse.
Thank you, kitties, I *guess*...